I would like to take the whole thing out (tube sections) But I can't figure out how to do that. I unbolted it at 2 locations but it appears to be heavily siliconed in where it meets the floor with a metal plate.
So I took off the motor, and the gear box. (gears look fine)

I then took the top cover off the tube. (again gears look fine) It is hard to tell but I believe the bottom gear maybe slipping on the shaft or the threaded shaft may have a bad spot. (stripped?)

I was able to get the top horizontal shaft and gear off,
But I can't seem to get the bottom gear off the main vertical shaft.
Don't see any pin.

There should be two carriage bolts holding it in place. Take them out and if necessary pry the clamps apart just a bit. The outer tube has a couple of upset places that locate it. Be sure to place a hydraulic jack under the frame so it does not collapse. The leg then comes out the top once you remove everything below. The inner most tube will fall out the bottom. It is very easy to do, but the assembly weighs about 30 pounds so be prepared for the weight. Take the motor and gear box off first to help reduce weight. All it takes is a philips screwdriver and I believe a 1/2 or 9/16 wrench.

Take the cap off. You will see a bevel gear facing on end. Tap the pin out and tap the shaft out of the housing. The gear below is sitting on a pin so all you need to do is lift it out, then with a pair of pliers remove that pin. Then with a soft hammer tap the shaft out the bottom of the leg. There is a cross piece that sits in a slot that acts as a guide for the top of the shaft. That also comes out easily. Now you have the screw and nut in your hands. I suspect you will find it cheaper to buy a complete new leg assembly direct from Venture Mfg. They will need the P/N and serial number from the metal cap at the top of the leg.
BT,DT. I just rebuilt my left leg as well. Just enough years and it was finally done. Luckily I had parts from my dual motor conversion project so it was only a matter of swapping parts from one leg to the other.
While your at it, and if your planning to keep this fiver for a while I would suggest the dual motor conversion and adding up limit switches to prevent jamming the legs and tearing up the gear box.

Thank you very much donn0128! That explains a lot.
That lower gear on mine must be stuck some how. I'm now suspecting that the sheer pin on that lower gear is what is impeding the removal.
When I take another crack at it, maybe next week, I'll let you know what I find.

I just went through the same deal. I did go with independent drives for right and left. The motor from Venture was much slower than the original but having independent drives has made leveling much easier.